Thanks for the KIP. I'm all for documenting the upgrade path like this. Just want to chime in on the Streams side of things, since there is (at least) one nuance which is probably worth accounting for:
Because of the introduction of cooperative rebalancing in 2.4 which was enabled by default for Kafka Streams, it is not possible to directly upgrade a Streams app from pre-2.4 to 2.4 or higher. Instead the user must follow a specific two-phase upgrade path, with the first rolling bounce setting the UPGRADE_FROM config and upgraded the bytecode, and the second rolling bounce simply removing the UPGRADE_FROM config. I mention this here because this means if a user needs to upgrade a Streams app from, say, version 1.0 to version 4.0 with 2.3 as a bridge release, they would have to go through 3 total upgrades instead of just 2. For this reason I'm wondering if we should recommend a slightly different upgrade path for Kafka Streams specifically: *[0.11.x - 2.3.x] → [2.4.x - 3.9.x] → 4.x* We should also call out the special upgrade path as part of the documentation here, that is, for all Kafka Streams users: 1. Set the UPGRADE_FROM config to the starting version and perform the *[0.11.x - 2.3.x] → [2.4.x - 3.9.x]* upgrade 2. Remove the UPGRADE_FROM config and perform the *[2.4.x - 3.9.x] → 4.x * upgrade Thoughts? On Wed, Jan 15, 2025 at 7:57 AM Chia-Ping Tsai <chia7...@gmail.com> wrote: > hi Kuan-Po > > thanks for raising this discussion. Some questions are listed below. > > chia00: > > in the `Upgrade Example`, could you pleas remind that the bridge version > must be compatible to server's version? > > chia01: > > could you please add link of KIP-896 in the "Proposed Changes"? > > Thanks, > Chia-Ping > > > Kuan Po Tseng <brandb...@gmail.com> 於 2025年1月15日 週三 下午9:46寫道： > > > Hi all, > > > > I'd like to initiate a discussion thread on *KIP-1124,* which proposes a > > clear upgrade path for Kafka Client, including Kafka Streams. > > You can find the details here: > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1124%3A+Providing+a+clear+Kafka+Client+upgrade+path > > I’d appreciate it if you could take a look and share your thoughts or > > feedback. > > > > Best regards, > > Kuan-Po Tseng > > >
